sonar question

[daemian]

Hi ppl,

I was thinking of using a sonar and sound sensor on a vehicle.The main problem is that since there is a lot of noise from the engine the sound sensor can't trace the sonar signal back again.Is there any way to make this noise signal more traceable?

thanks

 

[Nigel Goodwin]

Hi ppl,

I was thinking of using a sonar and sound sensor on a vehicle.The main problem is that since there is a lot of noise from the engine the sound sensor can't trace the sonar signal back again.Is there any way to make this noise signal more traceable?

You would normally use ultrasonic transducers for sonar on a vehicle, along with sharply tuned amplifier stages - this would reduce any engine noise.

 

[daemian]

You would normally use ultrasonic transducers for sonar on a vehicle, along with sharply tuned amplifier stages - this would reduce any engine noise.

:shock:

Thanks electronic god for the answer .I thought that ultrasonic transducer is proper for a distance of 20 meters long maximum.Could you please give more details about what ultrasonic transducers should i use(or where can i find them) and how could i implement sharply tuned amplifier stages(i am just a newbie but i have to know )?

 

[Russlk]

Look up info on bandpass amplifier and also crystal filter. There may be ceramic resonators that are in the band of interest.

 

[Nigel Goodwin]

Thanks electronic god for the answer .I thought that ultrasonic transducer is proper for a distance of 20 meters long maximum.Could you please give more details about what ultrasonic transducers should i use(or where can i find them) and how could i implement sharply tuned amplifier stages(i am just a newbie but i have to know )?

I would have thought 20m is probably approaching the maximum range, what sort of range do you require?.

If you do a google search for '+ultrasonic +sonar' you will find lots of useful information.

As to where you can buy transducers, you haven't filled your location in, so I've no idea what country you are in! - but they are freely available from any decent component supllier.

 

[pike]

I believe they use ultrasonics, instead because it is of higher frequency, therefore blocking the engine noise because it has a much lower frequncy.
The band pass filter allows the ultrasonic signals to pass but the lower frequency (engine noise) to be blocked.

 

[daemian]

I believe they use ultrasonics, instead because it is of higher frequency, therefore blocking the engine noise because it has a much lower frequncy.
The band pass filter allows the ultrasonic signals to pass but the lower frequency (engine noise) to be blocked.

Do i have to construct the band pass filter by myself or it is already build in the sonar?Also what is the top speed of a vehicle in order the sonar to be useful?

 

[Nigel Goodwin]

Do i have to construct the band pass filter by myself or it is already build in the sonar?Also what is the top speed of a vehicle in order the sonar to be useful?

What are you trying to do?.

Anything involving sonar is going to have to be fairly slow.

 

[daemian]

Well i am planning to use something for obstacle avoidance.The vehicle is going to move with a minimum speed of 30-40 km/h.

Any ideas how can i implement that?Laser maybe?

 

[tansis]

**broken link removed**

http://www4.cs.umanitoba.ca/~jacky/Teaching/Courses/74.795-LocalVision/ReadingList/fox97dynamic.pdf

The basic math for collision avoidance is ghastly to say the least,
and much of what has been written deals with much slower moving
robots, mainly because most ultrasonic rangefinders will only work to
around ten meters or so, lots of variables such as
air density/temperature/humidity/target size,velocity,direction of travel /aspect ratio and so on.

At the speeds you desire to achieve, well your onboard computer would
have less than a second to build a "mental" picture of its enviroment
then decided what action to take, an array of sensors might do it, just,
provided the vehicle did not skid to much when the brakes activate hard.


A scanning laser rangefinder... not easy to to build but a pair of them working together would give slightly better results.
**broken link removed**

It all really depends upon your budget, in recent months big names have thrown a lot "sponsorship" to talented teams, the results.....
Well you can read all about it the DARPA website.